Thank you @livius for you help. I didn't know there was an example for this in the repo from Pycom.

Anyway, I tried the OneWire and DS18X20 modules, but it always returns 60.25 or -7.5... while the ambient temperature should be around 19°C for now... Is this example working for you?

As for the memory, I used gc.mem_free() to see the available RAM memory, and as you said, it dropped very quickly. So, gc.collect() could be a workaround, but it just seem to freeze the Lopy... (it does not respond and I have to reset it with the reset button).